Our solar system may have once been made up of a number of super-Earths, until Jupiter came through the system like a giant wrecking ball, according to a new study.
The study by Caltech planetary scientist Konstantin Batygin and UC Santa Cruz professor of astronomy and astrophysics Gregory Laughlin suggests that the inner system used to contain a number of planets bigger than the Earth but smaller than Neptune.
"Our work suggests that Jupiter's inward-outward migration could have destroyed a first generation of planets and set the stage for the formation of the mass-depleted terrestrial planets that our solar system has today," Batygin says. "All of this fits beautifully with other recent developments in understanding how the solar system evolved, while filling in some gaps."
Recent surveys of exoplanets show that around half of the sun-like stars have orbiting planets, but the systems look vastly different from ours. Typically, they contain one or more worlds that are much more massive than the Earth orbiting closer to their suns with very little farther out. The low mass of the planets of our system have long puzzled scientists but make more sense if the planets are merely remnants of others broken apart by Jupiter.
"Indeed, it appears that the solar system today is not the common representative of the galactic planetary census. Instead we are something of an outlier," Batygin says. "But there is no reason to think that the dominant mode of planet formation throughout the galaxy should not have occurred here. It is more likely that subsequent changes have altered its original makeup."
It is possible that like other systems, our solar system originally formed planets close to the sun. When Jupiter headed in towards the sun, the gravitational forces shifted these planets into overlapping orbits causing them to smash into one another.
"It's the same thing we worry about if satellites were to be destroyed in low-Earth orbit. Their fragments would start smashing into other satellites and you'd risk a chain reaction of collisions. Our work indicates that Jupiter would have created just such a collisional cascade in the inner solar system," Laughlin said.
Jupiter barreling through the system helping destroy the planets in its path could be why today the inner planets of Mercury, Venus, Earth and Mars are all smaller sized with much thinner atmospheres.
"One of the predictions of our theory is that truly Earth-like planets, with solid surfaces and modest atmospheric pressures, are rare."
